Stringent government regulations mandate that food, beverage, and pharmaceutical manufacturers keep foreign material out of ingredients to ensure food and drug safety for consumers. Preventing foreign material from entering the processing stream is of the utmost concern but there must also be measures in place to detect contaminated product and quarantine it before distribution.
Component parts that are used in food and drug processing equipment can become damaged by improper installation and/or excessive shear experienced during operation that causes fragments of rubber, plastic, and metal to contaminate ingredients. Chemicals used for cleaning and sterilization of equipment can cause rubber seals to degrade, increasing
The static seals used in large energy and industrial facilities can be challenging to install and difficult to replace. They must, therefore, function flawlessly for periods longer than 20 years. Up until now, the existing tools used to calculate the long-term performance of sealing materials for these kinds of applications have often led to the components being larger than actually necessary.
Freudenberg Sealing Technologies has now developed a method that takes into account the material changes at the molecular level when predicting the long-term durability of seals. The new methodology is more reliable than previous models and ensure fewer materials to be used.
The seals used in plant engineering must have a very long service life. Once they are installed – to protect offshore wind turbine towers from salt corrosion, for example – customers typically require that they perfectly fit for more than 20 years. The service life of a seal is limited based on two things: First, by setting or stretching (physical relaxation). And second, chemical changes cause the material loses its elasticity over time.
Under the influence of atmospheric oxygen or ozone, two basic effects that influence the aging of seals can be observed: First, the polymer chains and networks can fracture under mechanical stress, and second, additional oxygen bridges can develop in the network as a result of oxidation processes. Both effects influence important properties of relevance for seals such as stiffness, contact pressures or the ability to regain their original shape after deformation, also referred to as resistance to deformation.
To determine whether a material actually meets the requirements for a specific application, engineers usually conduct so-called “storage tests” in which the test specimen is exposed to temperatures well over 100° C for a longer period of time – usually 1,000 hours – to predict temperature-dependent aging. Engineers typically extrapolate the measured values using the Arrhenius Equation, a method named after the Swedish chemist and Nobel Prize winner Svante August Arrhenius.
Article re-posted with permission from Parker Hannifin Sealing & Shielding Team.
Original content can be found on Parker’s Website and was written by Thorsten Kleinert, Business Unit Manager, Composite Sealing Systems Engineered Materials Group, Europe.
When classic sealing materials reach their limits, such as temperature ranges above 300°C and below -50°C – alternative materials are sometimes required, such as metal seals with appropriate coating/plating.
Parker offers metal seals made of stainless steel or nickel alloys in
The Style 204 family of spool-type expansion joints are manufactured with the industry standard narrow arch design. This style is intended to be used in dynamic conditions where both pressure and vacuum concerns are present.
Eclipse Engineering has in-house capabilities to manufacture seals up to 55 inches in diameter, and over 100 inches through production partners.
While seals with huge diameters certainly grant their own significant levels of intricacy, here we’ll look at the other end of the spectrum: the micro-sized seals.
We won’t just look at a simple seal ring, but an inherently more complicated and geometrically detailed spring energized seal. As we’ll see, very small diameters make multiple manufacturing aspects more involved and challenging.
A sealing solution in a customer's epoxy dispensing equipment. They needed an effective seal for the reciprocating rod responsible for the flow-control and metering of the epoxy while being dispensed.
In general terms, most viscous media sealing solutions have three things in common:
In most cases, multiple nested V-Springs are incorporated to provide optimal load and energize the compound contact points on the seal. With this formula, we’ve had great success sealing media like epoxy, urethane, silicones and acrylics.
The heavy loading is necessary to effectively wipe the reciprocating rod. This is balanced with the correct material and design geometry to provide long wear life of the seal, which has the potential to be compromised under such loading.
The challenge in this case was to incorporate these same proven principles in a micro-sized seal.
Oil and gas production and chemical manufacturing industries present sealing technologies with some of the harshest and most demanding operating environments.
"We screen Kalrez against some of the most aggressive corrosive fluids," says Dr Christopher Bish, Technical Fellow. "And in addition to the fluid testing, we did some compression set testing and stress relaxation testing at high temperatures. We now have one of the most chemically resistant and thermally stable compounds possible."
We screen Kalrez against some of the most aggressive corrosive fluids
One of the things that sets Dupont Kalrez apart is their quality control system, which gives them the ability to track materials as they flow through the plant. Scanning the barcode on the
A rubber expansion joint is likely the least understood and most abused component in a piping system. They are flexible, stretchy, and easily forced into lots of places despite what the installation instructions say. Most of the time, rubber expansion joints are merely an afterthought in a multimillion-dollar piping systems - until things go awry.
The rubber expansion joint is unmatched for vibration isolation. If properly installed, a rubber joint can greatly reduce equipment nozzle loads. Its resilience allows it to be installed in many different systems under a range of temperatures, pressures, and media. What could possibly go wrong?
Blame Murphy's Law if you want, the fates, or the alignment of planets. The reality of most failures is more straightforward. Most of the time, it is installation. More specifically, not following the manufacturer's instructions. See Images 1 to 7 illustrating the ugly aftermath of ignored installation instructions and unforeseen operating conditions.
Learn these lessons well so your piping system does not become the subject of another article.
Sometimes flexibility is a disadvantage. Why? Because it is easy to compress a joint into a space that is too small, which is exactly the problem in this example. The bead was damaged as the joint was forced into a gap between flanges, resulting in a seal failure. Spherical expansion joints rely on this bead to form a seal between flanges. If the bead is damaged, the building engineer will curse your name for eternity. Do not violate the face-to-face dimensions of an expansion joint.
Pipes misaligned? Think a bendy, stretchy rubber expansion joint will fix the situation? Thank again. This joint was installed between two misaligned flanges. A typical scenario may look like this:
Do not turn your pump room into a water park or, even worse, a sewage tank. Align those flanges before installing expansion joints.
Did you know water pumps can generate steam? This operator did not. In this unfortunate scenario (Image 4), the operator closed the pump isolation valves with the pump operating, dead-heading the pump. This situation is fine for a short duration, but eventually all that mechanical energy added to the water has to go somewhere. It went into heat. The water contained in the pump and pipe up to the isolation valves had so much energy added, that it flashed to steam. The expansion joint was the first component to fail, which was fortunate for the pump. The temperatures and pressures exceeded the rubber performance limits and the joint failed, nobly sacrificing itself for the greater good of the pump and piping.
Bacteria accumulation can ruin product and put consumer health at risk.
Bacteria accumulation is a serious issue in the food manufacturing industry - it can ruin product and put consumer health at risk.
While many know that Polytetrafluoroethylene (PTFE) is an excellent choice for use in diaphragms and gaskets, most do not realize that there exist varying grades of PTFE. Some lower cost PTFE offerings may contain an excessive volume of pores within their structure which can harbor organic contaminants such as bacteria.
To address this problem, a calendared manufacturing process is used. Calendared PTFE is a premium grade PTFE designed for use in aseptic applications requiring ultra-high purity standards. It is ideal for use in food, pharmaceuticals and a variety of clean markets.
Distinguished by an extremely low void content, calendared PTFE resists permeation and the accumulation of foreign matter, reducing the risk of harboring unwanted bacteria or residual media.
To achieve this, the unique manufacturing process orients the chains of PTFE in a lattice-like structure that reduces voids in the material and provides it with biaxial strength. This unique structure also delivers a very high flex life. When tested in an MIT Folding Endurance Tester, the flex life of calendared PTFE is four-times greater than conventional PTFE materials.
Unlike the skived process that is commonly used for PTFE manufacturing, the calendaring process produces uniform sheets of material with consistent physical properties. This gives calendared PTFE a renowned reputation for predictable performance and quality. The opposite is true for skived PTFE where variable properties lead to varying performance and reliability.
Article re-posted with permission from Parker Hannifin Sealing & Shielding Team.
Original content can be found on Parker’s Website and was written by Dr. Stefan Reichle, Market Unit Manager, Engineered Materials Group Europe.
Wherever drinking water is obtained from any of its sources, pumped and processed, materials with low extraction levels and without any harmful ingredients are required. Sealing compounds for use in drinking water and heating applications are subject to diverse approval regulations. These regulations serve to assure the safety